Passing parameters down to permanent redirect in ingress-nginx

Question

I'm using nginx.ingress.kubernetes.io/permanent-redirect: https://www.google.com but want to pass down parameters after / in the redirect. But can't get it to work with pure ingress-nginx, would be sweet if you could set /$1 or something similar. Is this possible with a mix of other annotations or tricks?

For example https://www.example.com/hello

Should redirect to https://www.google.com/hello

Answer 1

It's surprisingly easy:

apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
  name: test-ingress
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: /
    nginx.ingress.kubernetes.io/permanent-redirect: http://www.google.com$request_uri
spec:
  rules:
  - host: www.example.com
    http:
      paths:
      - path: /testpath
        pathType: Prefix
        backend:
          serviceName: test
          servicePort: 80

It leads to something like this in nginx.conf:

if ($uri ~* /) {
        return 301 http://www.google.com$request_uri;
}

It seems you can use any nginx variable in the address. So I guess you could do things like $scheme://www.google.com$request_uri as well :)

I first tried a nginx.ingress.kubernetes.io/server-snippet block like suggested in another answer here, but redirect 301 http://www.google.com$request_uri; hijacked too much in nginx.conf and stopped cert-manager from working. So I needed a better integrated solution.

If you want to debug, you can just look at nginx.conf yourself, it's really easy:

$ kubectl exec -n nginx-ingress nginx-ingress-controller-*** -- cat /etc/nginx/nginx.conf

Answer 2

It is possible to do this kind of redirection with following ingress.kubernetes.io/configuration-snippet configuration:

My ingress.yaml:

apiVersion: extensions/v1beta1
kind: Ingress
metadata:                                                                                                                                                  
  name: ingress-redirect
  annotations:
    nginx.ingress.kubernetes.io/server-snippet: |
      return 301 http://www.google.com$request_uri;
spec:
  rules:
  - host: www.example.com
    http:
      paths:
      - path: /
        backend:
          serviceName: servicename
          servicePort: 80

Apply ingress configuration:

$ kubectl apply -f ingress.yaml
ingress.extensions/ingress-redirect created

Verify ingress configuration and check its address.

$ kubectl describe ingress
Name:             ingress-redirect
Namespace:        default
Address:          10.156.0.33
Default backend:  default-http-backend:80 (<none>)
Rules:
  Host             Path  Backends
  ----             ----  --------
  www.example.com  
                   /   my-nginx:80 (<none>)
Annotations:
  kubectl.kubernetes.io/last-applied-configuration:  {"apiVersion":"extensions/v1beta1","kind":"Ingress","metadata":{"annotations":{"nginx.ingress.kubernetes.io/server-snippet":"return 301 http://www.google.com$request_uri;                                                                                                        \n"},"name":"ingress-redirect","namespace":"default"},"spec":{"rules":[{"host":"www.example.com","http":{"paths":[{"backend":{"serviceName":"my-nginx","servicePort":80},"path":"/"}]}}]}}

  nginx.ingress.kubernetes.io/server-snippet:  return 301 http://www.google.com$request_uri;                                                                                                        

Events:
  Type    Reason  Age                From                      Message
  ----    ------  ----               ----                      -------
  Normal  CREATE  33m                nginx-ingress-controller  Ingress default/ingress-redirect
  Normal  UPDATE  30m (x2 over 33m)  nginx-ingress-controller  Ingress default/ingress-redirect

And Finally test the if redirection works:

$ curl -v http://10.156.0.33/test/with?some=query -H "Host: www.example.com"
*   Trying 10.156.0.33...
* TCP_NODELAY set
* Connected to 10.156.0.33 (10.156.0.33) port 80 (#0)
> GET /test/with?some=query HTTP/1.1
> Host: www.example.com
> User-Agent: curl/7.52.1
> Accept: */*
> 
< HTTP/1.1 301 Moved Permanently
< Server: openresty/1.15.8.2
< Date: Wed, 27 Nov 2019 13:03:08 GMT
< Content-Type: text/html
< Content-Length: 175
< Connection: keep-alive
< Location: http://www.google.com/test/with?some=query
< 
<html>
<head><title>301 Moved Permanently</title></head>
<body>
<center><h1>301 Moved Permanently</h1></center>
<hr><center>openresty/1.15.8.2</center>
</body>
</html>
* Curl_http_done: called premature == 0
* Connection #0 to host 10.156.0.33 left intact

Make sure that Your ingress-controller is running properly and assigns IP address to ingress. Note that redirection works even without endpoint service.